In U.S. Pat. No. 4,081,651 apparatus is disclosed for supporting and rotating a pair of hollow tank sections of generally circular cross section, including scalene frusto-conical tank sections, during welding of the sections in end-to-end abutting relation to form an elongated tank. The apparatus includes three longitudinally spaced, axially aligned, rotatable ring which define a welding cage. The center ring includes a plurality of circumferentially spaced, radially directed jacks, each extendable the same distance regardless of the resistance encountered by a particular jack to force the abutting edges of the tank sections into a precise circular cross section and support and hold the abutting edges in aligned relation during rotation and welding. The two side rings include radially directed jacks in the bottom for lifting the sections and circumferentially spaced radially directed jacks of the seek-and-find type that will automatically extend until all jacks exert the same force on the tank sections extending from each side of the center ring to thereby support the tank sections for rotation about the common axis of the three rings, regardless of whether the tank sections are of cylindrical, right frusto-conical or scalene frusto-conical shape. A longitudinally extending conveyor is provided which extends within the welding cage and on either side of the welding cage for moving adjacent tank sections longitudinally toward each other into abutting engagement for welding, and for moving welded sections longitudinally of the cage.
However, after several courses have been circumferentially welded together the radially directed jacks in the outer ring supporting completed courses can no longer support and lift the welded courses into position for welding on an additional course.
The object of the present invention is to provide a support and lift assembly to work in conjunction with the radially directed jacks in the outer ring to move an assembly of several tank courses into position for welding on an additional tank course.
U.S. Pat. No. 3,480,158, in FIG. 1 illustrates circumferential welding of a pair of tanks 10 and 11 supported by rollers 12 and 16. The tanks are lifted into position by means of the roller supports 35 and 36 which are pivotably mounted at 33 and 34 upon the supports 26. Cylinders 43 and 46 having pistons 45 and 48 are thus used to lift the rolls into position.
However, this system has no provision for a scissors assembly to support cantilevered tank sections.
Moreover, it provides no accumulator and means for placing the accumulator in fluid communication with the cylinders as the courses are rotated for internal circumferential welding.